ParameterExpression

Returns a set of the unbound Parameters in the expression.

abs()

Absolute of a ParameterExpression

arccos()

Arccos of a ParameterExpression

arcsin()

Arcsin of a ParameterExpression

arctan()

Arctan of a ParameterExpression

assign(parameter, value)

Assign one parameter to a value, which can either be numeric or another parameter expression.

Parameters

• parameter (Parameter) – A parameter in this expression whose value will be updated.
• value (ParameterExpression |float) – The new value to bind to.

Returns

A new expression parameterized by any parameters which were not bound by assignment.

Return type

ParameterExpression

bind(parameter_values, allow_unknown_parameters=False)

Binds the provided set of parameters to their corresponding values.

Parameters

• parameter_values (dict) – Mapping of Parameter instances to the numeric value to which they will be bound.
• allow_unknown_parameters (bool) – If False, raises an error if parameter_values contains Parameters in the keys outside those present in the expression. If True, any such parameters are simply ignored.

Raises

• CircuitError –

  • If parameter_values contains Parameters outside those in self. - If a non-numeric value is passed in parameter_values.

• ZeroDivisionError –

  • If binding the provided values requires division by zero.

Returns

A new expression parameterized by any parameters which were not bound by parameter_values.

Return type

ParameterExpression

conjugate()

Return the conjugate.

Return type

ParameterExpression

cos()

Cosine of a ParameterExpression

exp()

Exponential of a ParameterExpression

gradient(param)

Get the derivative of a parameter expression w.r.t. a specified parameter expression.

Parameters

param (Parameter) – Parameter w.r.t. which we want to take the derivative

Returns

ParameterExpression representing the gradient of param_expr w.r.t. param or complex or float number

Return type

ParameterExpression | complex

is_real()

Return whether the expression is real

log()

Logarithm of a ParameterExpression

numeric()

Return a Python number representing this object, using the most restrictive of int, float and complex that is valid for this object.

In general, an int is only returned if the expression only involved symbolic integers. If floating-point values were used during the evaluation, the return value will be a float regardless of whether the represented value is an integer. This is because floating-point values “infect” symbolic computations by their inexact nature, and symbolic libraries will use inexact floating-point semantics not exact real-number semantics when they are involved. If you want to assert that all floating-point calculations were carried out at infinite precision (i.e. float could represent every intermediate value exactly), you can use float.is_integer() to check if the return float represents an integer and cast it using int if so. This would be an unusual pattern; typically one requires this by only ever using explicitly Rational objects while working with symbolic expressions.

This is more reliable and performant than using is_real() followed by calling float or complex, as in some cases is_real() needs to force a floating-point evaluation to determine an accurate result to work around bugs in the upstream symbolic libraries.

Returns

A Python number representing the object.

Raises

TypeError – if there are unbound parameters.

Return type

int | float | complex

sign()

Sign of a ParameterExpression

sin()

Sine of a ParameterExpression

subs(parameter_map, allow_unknown_parameters=False)

Returns a new Expression with replacement Parameters.

Parameters

• parameter_map (dict) – Mapping from Parameters in self to the ParameterExpression instances with which they should be replaced.
• allow_unknown_parameters (bool) – If False, raises an error if parameter_map contains Parameters in the keys outside those present in the expression. If True, any such parameters are simply ignored.

Raises

CircuitError –

• If parameter_map contains Parameters outside those in self. - If the replacement Parameters in parameter_map would result in a name conflict in the generated expression.

Returns

A new expression with the specified parameters replaced.

Return type

ParameterExpression

sympify()

Return symbolic expression as a raw Sympy or Symengine object.

Symengine is used preferentially; if both are available, the result will always be a symengine object. Symengine is a separate library but has integration with Sympy.

tan()

Tangent of a ParameterExpression